1. Field of the Invention
The present invention relates to a small size liquid crystal display device, a portable terminal and display equipment provided with such a liquid crystal display device.
2. Description of the Related Art
Conventional STN type liquid crystal displays P1 and P2 are now discussed referring to FIGS. 47–52.
FIG. 47A is a plan view of the liquid crystal display P1. FIG. 47B is a right-side view of the same, and FIG. 47C is an upper-side view of the same. The liquid crystal display P1 is arranged such that two rectangularly shaped glass substrates are joined together. There are provided two driver ICs (not shown) one of which is for segment electrodes, and the other is for common electrodes. The driver ICs are disposed along two sides of the glass substrate 1 external to the respective sides. When mounting the driver ICs on the body substrate, TCP (Tape Carrier Package) or COF (Chip on Film) is used. (Refer to Japanese Unexamined Patent Publication H08-179348.)
On the glass substrate 2, a group of transparent common electrodes 4 and a wiring pattern 5 with a trapezoidal shape which extends from the transparent common electrode group 4 are provided. On the other glass substrate 1, there are provided a group of transparent segment electrodes 10, and a wiring pattern 9 with a trapezoidal shape which extends from the transparent segment electrode group 10. The area where the transparent common electrode group 4 and the transparent segment electrode group 10 cross each other form a display area 3.
On edges of two sides of the glass substrate 1, there are provided common-side terminal group 6 connected with the wiring pattern 5, and segment-side terminal group 8 connected with the wiring pattern 9. TCPs or COFs are mounted on the common-side terminal group 6 and segment-side terminal group 8 by thermal pressure using an anisotropic conductive film.
A sealing resin 7 is provided external to the display area 3 so as to surround the display area 3. The glass substrates 1 and 2 are bonded together with the sealing resin 7, and the internal space between them is filled with a liquid crystal 12 by injecting it through an injection inlet 13. Then, it is sealed with a UV curable resin 11.
When the number of pixels is represented by m×n, since one pixel is constituted of three kinds of colors i.e. R (red), G (green) and B (blue) in the colorized liquid crystal display device P, the number of transparent segment electrodes 10 to be provided is 3m. The numbers of wires in the wiring patterns 9 and segment-side terminals 8 are also 3m. The numbers of transparent common electrodes 4, wires in the wiring pattern 5 and common-side terminals 6 are n, respectively. These are shown with a part thereof omitted in the drawings.
FIG. 48 is a cross-sectional view taken along the line a—a in FIG. 47A.
The sealing resin 7 contains conductive particles 14. The common-side terminal group 6 and the wiring pattern 5 are connected vertically by the conductive particles 14. The portions connecting them vertically are referred to as “conduction portions between substrates.”
On the transparent common electrode group 4, an alignment film 23 for aligning the liquid crystal 12 is formed. Also, an alignment film 24 is formed on the transparent segment electrode group 10. Between the alignment films 23 and 24, spacers 45 are dispersed in order to keep the gap S between the substrates at a constant distance.
In the above-mentioned liquid crystal display device P1, however, the arrangement is such that two driver ICs one of which is for segment electrodes and the other for common electrodes are mounted along and external to two sides of the assembly of two rectangularly shaped glass substrates bonded together. Accordingly, two driver ICs are required in this structure.
Accordingly, it has been desired to integrate the functions of both of the driver ICs into one driver IC thereby reducing the IC cost and the mounting cost.
A liquid crystal display device P2 provided with one driver IC prepared in the above-mentioned way is now described.
FIG. 49A is a plan view of the liquid crystal display device P2. FIG. 49B is a right-side view of the same, and FIG. 49C is an upper-side view of the same. FIG. 50 is an enlarged view of an essential part B shown in FIG. 49A. FIG. 51 is a cross-sectional view taken along the line c—c in FIG. 50. FIG. 52 is a cross-sectional view taken along the line d—d in FIG. 50. In these drawings, parts corresponding to those in the liquid crystal display device P1 described above are denoted by the same reference characters.
As shown in FIG. 49A, the display area 3 is divided into the upper area and the lower area. The transparent common electrode group 4 in the upper area is drawn to the right side, and the transparent common electrode group 4 in the lower area is drawn to the left side. They are connected to the wiring patterns 5A and 5B, respectively, on the glass substrate 2. These wiring patterns 5A and 5B are extended to the conduction portions between substrates Q21 and Q22, respectively.
The conduction portions between substrates Q21 and Q22 are provided for electrically connecting the wiring patterns 5A, 5B on the glass substrate 2 to the wiring pattern 20 on the glass substrate 1. In this example, the sealing resin 7 containing conductive particles 14 is used for these portions as shown in FIG. 51.
The wiring pattern 20 is a pattern made of ITO, which spreads in the form of a trapezoid. The wiring pattern 20 is connected to the common-side terminal group 6 disposed on the both sides of the segment-side terminal group 8. In the conduction portions between substrates Q21 and Q22, in order to stably connect the upper and lower electrodes to each other with low resistance to conduction by bringing them into contact with many conductive particles 14, the wiring width D of the wiring patterns 5 and 20 needs to be as large as possible. In addition, in order to prevent the conductive particles 14 from causing short-circuit among adjacent wires, a spacing S larger than a specific distance is required between each of the wires (See FIG. 52).
Accordingly, under the present circumstances, wiring pitch P (P=wiring width D+wiring spacing S) in the conduction portions between substrates Q21 and Q22 is made larger than the wiring pitch (in the order of 60 μm) of the common-side terminal group 6.
It is therefore necessary to provide an area (represented by the size L in FIG. 49A) for routing the wiring pattern 20 spreading from the common-side terminal group 6 in the form of a sector.
This makes the longitudinal size of the panel large, failing to meet the recent market demand for downsizing. For example, such a panel is inconvenient to be used as LCD panel for mobile phone in which the panel dimensions are restricted.
In addition, regarding small size liquid crystal display devices for mobile phones, it is often the case that wiring patterns 5 and 9 are viewable from the display surface due to its small area. When the wiring patterns 5 and 9 are formed of a metal material, light reflected from the patterns deteriorates the visibility. Improvement in this respect is also anticipated.
It is an object of this invention to provide a liquid crystal display device capable of accomplishing downsizing thereof by reduced dimensions.
It is another object of this invention to provide a liquid crystal display device which is suitable for a portable terminal such as mobile phone.
It is still another object of this invention to provide display equipment in which downsizing thereof is accomplished.
It is still another object of this invention to provide a liquid crystal display device with good visibility.